How does filament silk thread differ from spun silk thread?
A technical question than is more important than you can imagine. Filament silk threads are continuous fibers, twisted, only, to make them easier to use. Spun silk threads (the broken, lower quality waste silk fibers) must be twisted to make them stay twisted. The shorter spun silk fibers can easily become shredded or untwisted, while the filaments will stay in tact.